Project Summary The proposed study will investigate the impact of foster care, and specific experiences within foster care, on the physical and mental health of children exposed to abuse or neglect. This population is among the most vulnerable in the U.S., with a disproportionately high prevalence of adverse health and wellbeing outcomes throughout the life course. The Aims of this proposal are: (1) Examine the effects of foster care on health over time; (2) Investigate the influence of placement experiences on foster children's health during and after exiting foster care; and (3) Evaluate the effects of maintaining family connections on foster children's health during and after exiting foster care. Prior research in this area has suffered one or more significant limitations, including: threats to causal inference; cross-sectional, short-term, or discrete observation periods; small or non-representative samples; reliance on caregiver-reported health outcomes; and a lack of focus on physical health. This proposal seeks to address these limitations and provide sound empirical evidence on the role of foster care in children's immediate and longer-tem health. In Aim 1, we focus on how foster care impacts children's physical and mental health outcomes over time, as compared with children involved with the child protection system but who remain in their familial homes. Using linked Medicaid and child protection records, we will observe significant health events before, during, and after foster care. Using methods intended to improve causal inference, we will be able to not only identify the impacts of foster care on health, but also understand whether those impacts are temporary or sustained. In Aims 2 and 3, we focus on the experiences of children within foster care that produce heterogeneity in health outcomes. To maximize the potential of our findings to inform efforts to improve foster children's health and wellbeing, we emphasize foster care experiences that are current priorities of federal and state reforms, including placement setting (e.g., with relatives, in group homes), placement stability, placement with siblings, and parent and sibling visitation. Again leveraging Medicaid and child protection records, and with a focus on causal inference, we will provide compelling evidence on whether the current priorities of the foster care system serve to enhance children's health. Such evidence is essential to the effective allocation of scarce resources.